Dynamic Performance Analysis of p-GaN HEMTs With Floating Substrates by Substrate Capacitance Coupling Model

A comprehensive and in-depth evaluation of the dynamic characteristics of p-GaN high-electron-mobility transistor (HEMT) components featuring a floating substrate is carried out, contrasting with devices having a source-connected substrate in traditional applications. A thorough analysis reveals similar degradation patterns of both devices but varying degrees of dynamic performance deterioration under transient stress. Experimental results show that under 200-V <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {DS,off}}$ </tex-math></inline-formula> stress, devices with floating substrates experience a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {TH}}$ </tex-math></inline-formula> shift of 2.6 V and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {on}}$ </tex-math></inline-formula> degradation of 30%, while those with source-connected substrates exhibit a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${V}_{\text {TH}}$ </tex-math></inline-formula> shift of 1.15 V and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {on}}$ </tex-math></inline-formula> degradation of 7%. A proposed capacitance coupling model specific to floating substrates explains the suboptimal dynamic performance. The negative substrate voltage, induced by capacitor charge imbalances during <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small>-state stress, is a key factor affecting device performance. Understanding the sequence of hole and electron capture, along with dynamic resistance variations, is crucial for maximizing the advantages of p-GaN HEMTs with floating substrates.